甲醛扩散管的准确性分析

目的 考察甲醛扩散管作为气体发生源的准确性。方法 选择3支甲醛扩散管,用AHMT比色法作为参比方法测定甲醛扩散管的扩散率,比较重量法和比色法的测定结果。对扩散管配制甲醛标准气体的准确性进行分析。结果 三聚甲醛热分解成单分子甲醛的效率达到99%以上,其相对标准偏差为0.40%。方法的不确定度小于5%（95%置信区间）。结论 扩散管作为配制甲醛标准气体的发生源是准确可靠的。

Analysis of Accuracy of the Formaldehyde Diffusion Tube

Objective To study the reliability of the formaldehyde diffusion tube as a standard gas generating source. Methods Three diffusion tubes with different diffusion ratios were selected and the diffusion ratios were determined using the reference method,viz. AHMT colorimetry, and the results were compared with those obtained by gravimetric analysis. The accuracy of standard gases generated by the formaldehyde diffusion tube was analyzed. Results The thermal decomposition efficiency of trioxane turning into monomolecular formaldehyde was more than 99%, and the relative standard deviation was 0.40%. The uncertainty of AHMT colorimetry was less than 5% with a confidence limit of 95%. Conclusion The formaldehyde diffusion tube was precise and reliable as a standard gas generating source.